The present invention relates to an analogue balancing system for an assembly of capacitive-effect storage devices connected together in series. It also relates to a rechargeable electrical energy storage module, an electric vehicle and an electrical supply installation implementing such a system.
The field of the invention is the field of means for balancing supercapacitors connected in series.
A supercapacitor performs capacitive-effect electrical energy storage. The main limitation of a supercapacitor is that it only operates at very low voltage. In order to reach the desired operating voltage, supercapacitors are placed in series in a rechargeable electrical energy storage module.
However, due to manufacturing differences or ageing differences, the supercapacitors of one and the same storage module only rarely charge at the same speed. In order to ensure a greater homogeneity of voltage at the terminals of the supercapacitors in series, a balancing system is provided, in an analogue form for reasons of cost, reliability, feasibility and robustness.
This analogue balancing system provides for diverting, during a charging phase, at least a portion of the current for each supercapacitor, individually, when the voltage at its terminals exceeds a predetermined voltage called balancing voltage. At the end of the charging phase, if the balancing voltage is exceeded for all the supercapacitors, which is generally the case, all the supercapacitors are therefore by-passed.
Thus, when the charging phase is not immediately followed by a discharge phase, but by a voltage maintenance phase or a rest phase, each supercapacitor remains by-passed and discharges to the bypass circuit while the voltage at its terminals is greater than the balancing voltage. In other words, during a voltage maintenance phase, or rest phase, separating a charging phase from a discharge phase, the supercapacitors discharge to the bypass circuit when they are not in use. Due to this, a loss of energy takes place, compensated in the case of a voltage maintenance phase, not compensated in the case of a rest phase, which is costly in all cases, and reduces the efficiency and the autonomy of the supercapacitors, and therefore of the storage module.
An aim of the present invention is to overcome these drawbacks.
Another aim of the invention is to propose a balancing system that is more efficient for an assembly of capacitive-effect storage devices in series.
It is also an aim of the invention to propose a balancing system for an assembly of capacitive-effect storage devices in series making it possible to reduce, or even eliminate, the energy losses, and to increase the efficiency and the operating range of said assembly.